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2016 schedule

Jonathan Powles (for Carl Knight)

Variable Stars South

Betelgeuse is a highly-evolved red supergiant with multiple modes of pulsation and variability in V. With a surface temperature around 3000 K, its peak emission lies in the near infra-red (IR). Some features, such as its large convective cells, are only visible in near IR. It is a candidate for the next type II supernova in our neighbourhood. It has attracted considerable professional interest but, with a V magnitude less than 0.5, J magnitude less than -2.99 and H less than -3.99, it is much too bright for professional observatories. In this presentation, the case is made for amateur photometric observations, particularly in the J and H near IR bands.

Jonathan Powles is an amateur astronomer based in Canberra. He has been active as a variable star observer and amateur spectroscopist since 2012. Observations are made with a 10" SCT on his balcony in suburban Canberra, which is often coupled to a Ken Harrison-designed Spectra L200 spectroscope. He is active as an observer of eclipsing binary stars, cataclysmic variables, novae, and emission-line stars. For his day job, he has had a career as a music and education academic, and is currently Director of Teaching and Learning at the University of Canberra.

Carl Knight is a computer programmer by profession and variable star observer by obsession. He lives in the rural Rangitikei district in New Zealand with his wife, children and a menagerie of farm animals. He first became interested in observing stars in the near infra-red when he became the latest custodian of an otherwise idle AAVSO J and H band photometer. Determined to see the instrument used he researched targets to which the instrument is particularly suited. His primary interests in variable stars are all various forms of late stellar evolution. The near infra-red is ideal for these late class stars. SRC variables such as Betelgeuse are poorly understood in many respects. He hopes to add greatly to the quality of the data the amateur community can provide and to advance our understanding of this important class of stars.